As a result, the LLC-1 cancer cells with reduced metabolism were arrested at the S-phase of the cell cycle via activation of the Skp2 autoinduction loop, induction of ERK-p53 signaling, suppression of cdk/cyclin complexes via cdk inhibitors of p21 and p27, and induction of genotoxic stress (Figure 7D). Here, PCNA is linked to cancer.